Flat strip lamella for reinforcing building components and method for placing a flat strip lamella on a component

ABSTRACT

Flat strip lamella ( 10 ) for reinforcing load-bearing or load transferring building components e.g. concrete, wood, steel, natural stone or masonry. The flat strip lamella ( 10 ) has a composite structure consisting of a plurality of parallel aligned, bendable or flexible carrying fibers ( 26 ) and a binding matrix ( 28 ) joining the carrying fibers to each other and making them shear resistant. The lamella can be attached facewise to the surface of the building component to be reinforced, using adhesive ( 16 ). In order to be able to bend the flat strip lamella over corner edges of a building component, the binding matrix ( 28 ) consists of a thermoplastic synthetic material.

DESCRIPTION

[0001] The invention concerns a flat strip lamella for reinforcingload-bearing or load-transmitting building components, which iscomprised of a composite structure of a plurality of bendable orflexible reinforcing fibers aligned parallel to each other and a bindermatrix which joins the reinforcing fibers to each other in a shearresistant manner, and which can be attached facewise to the outersurface of the building components by means of an adhesive. Theinvention further concerns a process for application of this type offlat strip lamella onto a building component.

[0002] Reinforcing lamellas of this type are known, for example, from WO96/21785. The therein disclosed reinforcing lamellas are applied tolongitudinally extending and/or flat surfaced construction components.The reinforcing lamellas hardened with a binder matrix of a Duroplast,in particular epoxy resin, do not permit a bending with a small bendingradius, so that it is not possible to form a bowed reinforcementextending over a corner of a construction component. Bowedreinforcements or sheaths are necessary for example in order to securethe connection or interrelation between the compressive and tensilezones in steel reinforced concrete girders or steel reinforced concreteT-beams and to avoid stress and transverse fractures.

[0003] Beginning therewith the present invention is concerned with atask of developing a flat strip lamella which can reinforce aconstruction component by extending over a corner thereof. A furthertask of the invention is comprised in the development of a process forthe application of this type of flat strip lamella to constructioncomponents.

[0004] For solving this task the combination of characteristics setforth in claim 1 as well as 6 through 9 is proposed. Advantageousembodiments and further developments of the invention can be seen fromthe dependent claims.

[0005] The inventive solution is based on the recognition, that thebending flexibility of the flat strip lamellas is determined primarilyby the binder matrix. In order to be able to guide the flat striplamella also over bent construction component outer surfaces andbuilding component corners, it is proposed in accordance with theinvention, that the binder matrix be comprised of a thermoplastic resin.This type of flat strip lamella can be deformed by application of alocal temperature increase and then fitted to the outer surface contourof the construction component to be reinforced. The glass transitionpoint of the employed thermoplastic resin is preferably above 100° C.,while the melting point should begin above 160° C., in order that areliable manipulation is achieved. The local heating of the flat striplamella can be achieved on site with the aid of a hot air gun.

[0006] For forming the binder matrix one can consider for example athermoplastic resin from the group consisting of polyolefins,vinylpolymers, polyamide, polyester, polyoxymethylene, polycarbonate andthermoplastic polyurethane and ionomers.

[0007] The reinforcing fibers are preferably formed of carbon fibers,which are characterized by a high modulus of elasticity. The reinforcingfibers can however contain or be comprised of aramid fibers, glassfibers, polypropylene fibers and the like.

[0008] For application of the inventive longitudinally extending flatstrip lamella over a corner of a construction component to be reinforcedit is proposed in accordance with the invention that the flat striplamella is heated in the intermediate area to be directed over thecorner of the construction component to a temperature above the glasstransition point of the thermoplastic binder, that it is bent in theheated condition at an angle corresponding to that of the corner or edgeangle of the construction component, and that before or after cooling itis adhered to the construction component over the construction edge bymeans of a adhesive layer.

[0009] The inventive application of a thermoplastic binder matrix makesit possible to apply the flat strip lamellas in the pretensionedcondition to a construction component outer surface. The free ends ofthe flat strip lamellas which project beyond the surface of theconstruction component to be reinforced can, in their heated state, bedrawn or stretched with a tensioning element or be bent and fixedthereupon. The tensioning elements can then be tensioned against eachother so that the flat strip lamella can be adhered to the constructioncomponent outer surface in the pretensioned condition. For tensioning ofthe tensioning elements a tensioning mechanism can be provided spacedapart from the construction component. The tensioning mechanism couldalso engage only at the free end of the flat strip lamella, when theother end is fixed to the construction component outer surface by asuitable tensioning element.

[0010] Further there exists with the inventive thermoplastic bindermatrix the possibility of pressing the free ends of the flat striplamella under the action of pressure and heat into a wave or zigzagshape. To achieve a form-fitting anchoring, the lamella ends deformed inthis manner are introduced into a recess in the construction componentfilled with adhesive, so that the zigzag area fills with the pastyadhesive and after hardening of the adhesive forms a form fittingconnection.

[0011] The flat strip lamella with the inventive thermoplastic bindermatrix can additionally be employed for reinforcement of column-shapedconstruction components. Therein the flat strip lamella heated to atemperature above the glass transition point of the binder matrix iswound in a spiral manner about a column-shaped construction component ofwhich the outer surface is coated with fluid reaction adhesive and inthis wound state is cooled to room temperature with simultaneoushardening of the adhesive. In order to avoid collection of liquids belowthe flat strip lamella winding, it is advantageous, when a separation ismaintained between the spiral windings of the flat strip lamella.

[0012] In order to improve the bond between the flat strip lamella andthe adhesive, such as epoxy resin, it can be advantageous, when the flatstrip lamella is freed of binder with simultaneous exposure of thereinforcing fibers on the side to be adhered, for example by rougheningor grinding.

[0013] In the following the invention will be described in greaterdetail by reference to the embodiment shown in schematic manner in thedrawings. There is shown

[0014]FIG. 1a a top view of a section of a reinforcing lamella;

[0015]FIG. 1b an enlarged representation of a section along section lineB-B of FIG. 1a;

[0016]FIG. 2 a section through a steel reinforced concrete T-beam withbow-shaped bent reinforcing lamella;

[0017]FIG. 3 the one end of the reinforcing lamella, which can beintroduced into the recess in the construction component according tosection III of FIG. 2;

[0018]FIG. 4 a tensioning device for pretensioned application of thereinforcing lamella to a construction component;

[0019]FIG. 5 a sectional side view of a column-shaped constructioncomponent with a reinforcing lamella wound about in spiral manner.

[0020] The flat strip lamellas 10 shown in the drawings are designed forpost reinforcement of construction components 12, such as steelreinforced concrete structures and masonry structures. They are securedat one of their face sides 14 against the outer surface of theconstruction component with the aid of an adhesive 16, preferably anepoxy resin, and supplementally anchored at their free ends 32, 34 tothe construction component 12 (FIG. 2).

[0021] The construction component 12 according to FIG. 2 is formed inthis example as a steel reinforced concrete T-beam, in which the lamella10 extends in a bow like manner over the cross beam 22 of theconstruction component 12 and thereby is bent over the corner edges 24of the cross beam 22.

[0022] The flat strip lamella 10 has a composite structure of aplurality of parallel aligned bendable or flexible reinforcing fibers 26of carbon fiber and of a binder matrix which joins the reinforcingfibers in a shear resistant manner, the binder matrix being comprised ofa thermoplastic resin. The thermoplastic binder matrix 28 ensures thatthe flat strip lamella is relatively stiff at temperatures of use and isplastically deformable upon heating to a temperature above the glasstransition point. In order to initially guide the longitudinallyextending flat strip lamellas 10 over the corners 24, they are heated inthe intermediate area 30 to a temperature above the glass transitionpoint of the thermoplastic binder matrix and plastically bent about theedge angle, which may be rounded off, at approximately 90°. This bendremains retained after the cooling to the temperature of use.

[0023] In the illustrative embodiment shown in FIG. 2 the plasticdeformability under increased temperature of one end 32 of the flatstrip lamella is also taken advantage of in the anchoring process. Thebent-away end 32 is adhered to the construction component 12 with anadhesive 16. At its other free end 34, the flat strip lamella exhibits azigzag-shaped deformation, with was produced under the action ofpressure and heat. With this end 34 the flat lamella 10 penetrates intoan adhesive filled recess 35 of the construction component 10 and formsa formfitting anchoring upon hardening of the adhesive in this recess.

[0024] In the embodiment shown in FIG. 4 the free ends 36 of the flatstrip lamella 10 are drawn in the heated, plastic deformed conditionupon drum-shaped tensioning elements 38 and are anchored there. Thetensioning elements 38 can, under the influence of a suitable tensioningmechanism, be displaced in the direction of the double arrow 39 towardseach other so that the flat strip lamella 10 is pretensioned duringadhering to the construction component 12 with the aid of the adhesive16. If the pretensioning is maintained until the hardening of theadhesive, one attains an improvement in the reinforcing effect.

[0025] In the embodiment shown in FIG. 5 a flat strip lamella 10 iswound in a spiral manner upon a column-shaped construction component 12and adhered thereto. In order to facilitate the winding, the flat striplamella is subjected to an elevated temperature, so that during windingit can easily be brought to its spiral shape.

[0026] In summary the following is to be concluded: The inventionconcerns a flat strip lamella 10 for reinforcing load-bearing orload-transmitting building components e.g. concrete, wood, steel,natural stone or masonry. The flat strip lamella 10 has a compositestructure consisting of a plurality of parallel aligned, bendable orflexible carrying fibers 26 and a binding matrix 28 joining the carryingfibers to each other and making them shear resistant. The lamella can beattached facewise to the surface of the building component to bereinforced, using adhesive 16. In order to be able to bend the flatstrip lamella over corner edges of a building component, it is proposedin accordance with the invention that the binding matrix 28 consists ofa thermoplastic resin material.

1. Flat strip lamella for reinforcing load-bearing or load-transmitting building components (12), preferably comprised of concrete, which comprises a composite structure of a plurality of parallel-aligned bendable or flexible reinforcing fibers (26) and a binder matrix (28) which joins the reinforcing fibers in a shear-resistant manner, and which can be attached facewise to the outer surface of the reinforcing construction component (12) by means of an adhesive (16), characterized therein, that the binding matrix (28) consists of a thermoplastic resin.
 2. Flat strip lamella according to claim 1, characterized therein, that the glass transition point of the thermoplastic resin is at least 100° C. and the melting point is at least 160° C.
 3. Flat strip lamella according to claim 1 or 2, characterized therein, that the thermoplastic resin is selected from the group consisting of polyolefins, vinylpolymers, polyamide, polyester, polyacetale, polycarbonate, polyurethane and ionomers.
 4. Flat strip lamella according to one of claims 1 through 3, characterized therein, that the reinforcing fibers are or include carbon fibers.
 5. Flat strip lamella according to one of claims 1 through 4, characterized therein, that the carrying fibers are or include aramid fibers, glass fibers or polypropylene fibers.
 6. Method for attachment of a premanufactured longitudinally extending flat strip lamella according to one of claims 1 through 5 to a construction component (12) over at least one corner edge (24), characterized therein, that the flat strip lamella is heated in the intermediate area (30) to be applied over the corner (24) of the construction component to a temperature above the glass transition point of the thermoplastic binder, that it is bent in the heated condition at an angle corresponding to that of the corner or edge angle of the construction component, and that before or after cooling it is adhered to the construction component over the construction edge by means of a adhesive layer (16).
 7. Method for attachment of a premanufactured flat strip lamella according to one of claims 1 through 5 to a construction component surface, characterized therein, that the flat strip lamella (10) with each free end in a heated condition is drawn or bent upon a respective tensioning element, and is arrested thereto, and that the tensioning elements (38) are tensioned against each other and the flat strip lamella (10) is adhered to the construction component surface in this pretensioned condition.
 8. Method for attachment of a flat strip lamella according to one of claims 1 through 5 to a construction component with the aid of an adhesive, characterized therein, that a wave or zigzag shape is pressed in into the free ends (34) of the flat strip lamella (10) under the application of pressure and heat, and while inserting the lamella ends (34) into a construction component recess the wave or zigzag areas are filled with adhesive under production of a form fitting connection.
 9. Method for attachment of a flat strip lamella according to one of claims 1 through 5 to an construction component with the aid of an adhesive, characterized therein, that the flat strip lamella is heated to a temperature above the glass transition pint of the binder is wound in a spiral manner about a column-shaped construction component and in this wound state is cooled to room temperature with simultaneous hardening of the adhesive.
 10. Method according to one of claims 6 through 9, characterized therein, that the reinforcing fibers (26) are at least partially exposed by removal of binder (28) from the surface of the side which is to be connected with the construction component. 